1. Field of the Invention
The present invention relates to a pointed position detection device and a pointed position detection method for detecting a position irradiated by a pointing light by a laser beam from a pointer device, etc. on a projected image on a screen.
2. Description of the Related Art
Conventionally, a projector has been used for projecting an explanatory image created by, for example, a personal computer on a screen in enlargement, in a presentation for project explanation or product description, or a lecture for presenting research results, etc. As a method of projecting an image in color, there is a method called field sequential color method. The field sequential color method is a method for projecting an R image, a G image, and a B image on a screen alternately and quickly in a cycle, thereby making human eyes perceive a color image. A projector which employs an optical modulator for embedding image information output from a personal computer on a light beam, has been put into practical use, as a projector of the field sequential color method. A DMD (Digital Micromirror Device) is used as the optical modulator. Such a projector comprises a color wheel in addition to the DMD. The color wheel is a rotatable color filter which is divided into areas for R (red), G (green), and B (blue) in the rotation direction. The color wheel generates an R image, a G image, and a B image by permitting a light of a color image from a light source to permeate therethrough. The projector focuses the light of the color image from the light source onto the DMD through the color wheel while rotating the color wheel. The projector mechanically drives the DMD in synchronization with the rotation of the color wheel, and reflects the focused R image, G image, and B image on the DMD to project a projection light of each of the R, G, and B images on the screen.
In the meantime, in a case where a projector is used in a presentation, etc., it is common that the presenter or the lecturer points to an arbitrary position on the projected image on the screen by using a laser pointer and irradiating a laser beam (generally, red-colored) emitted therefrom onto the screen.
However, in a case where one tries to detect the position pointed by the laser pointer with the use of an area sensor such as a CCD, etc., there has occurred the following problem. That is, in a case where the laser beam emitted from the laser pointer is, for example, red, and the projected image on the screen includes a red portion, it is difficult to detect only the optical image of the laser beam.